﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net.Security;
using System.Security.Cryptography.X509Certificates;
using System.Net;
using System.IO;
using System.IO.Compression;
using System.Text.RegularExpressions;  

namespace WebCrawler
{
    class HttpWebResponseUtility
    {

        //private static readonly string DefaultUserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)"; 
        private static readonly string DefaultUserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.31 (KHTML, like Gecko) Chrome/26.0.1410.43 Safari/537.31";
        /// <summary>  
        /// 创建GET方式的HTTP请求  
        /// </summary>  
        /// <param name="url">请求的URL</param>  
        /// <param name="timeout">请求的超时时间</param>  
        /// <param name="userAgent">请求的客户端浏览器信息，可以为空</param>  
        /// <param name="cookies">随同HTTP请求发送的Cookie信息，如果不需要身份验证可以为空</param>  
        /// <returns></returns>  
        public static HttpWebResponse CreateGetHttpResponse(string url,int? timeout, string userAgent,CookieCollection cookies)  
        {  
            if (string.IsNullOrEmpty(url))  
            {  
                throw new ArgumentNullException("url");  
            }  
            HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;  
            request.Method = "GET";  
            request.UserAgent = DefaultUserAgent;  
            if (!string.IsNullOrEmpty(userAgent))  
            {  
                request.UserAgent = userAgent;  
            }  
            if (timeout.HasValue)  
            {  
                request.Timeout = timeout.Value;  
            }  
            if (cookies != null)  
            {  
                request.CookieContainer = new CookieContainer();  
                request.CookieContainer.Add(cookies);  
            }  
            return request.GetResponse() as HttpWebResponse;  
        }  
        /// <summary>  
        /// 创建POST方式的HTTP请求  
        /// </summary>  
        /// <param name="url">请求的URL</param>  
        /// <param name="parameters">随同请求POST的参数名称及参数值字典</param>  
        /// <param name="timeout">请求的超时时间</param>  
        /// <param name="userAgent">请求的客户端浏览器信息，可以为空</param>  
        /// <param name="requestEncoding">发送HTTP请求时所用的编码</param>  
        /// <param name="cookies">随同HTTP请求发送的Cookie信息，如果不需要身份验证可以为空</param>  
        /// <returns></returns>  
        public static HttpWebResponse CreatePostHttpResponse(string url,IDictionary<string,string> parameters,int? timeout, string userAgent,Encoding requestEncoding,CookieCollection cookies)  
        {  
            if (string.IsNullOrEmpty(url))  
            {  
                throw new ArgumentNullException("url");  
            }  
            if(requestEncoding==null)  
            {  
                throw new ArgumentNullException("requestEncoding");  
            }  
            HttpWebRequest request=null;  
            //如果是发送HTTPS请求  
            if(url.StartsWith("https",StringComparison.OrdinalIgnoreCase))  
            {  
                ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);  
                request = WebRequest.Create(url) as HttpWebRequest;  
                request.ProtocolVersion=HttpVersion.Version10;  
            }  
            else  
            {  
                request = WebRequest.Create(url) as HttpWebRequest;  
            }
            request.Method = "POST";  
            request.ContentType = "application/x-www-form-urlencoded";
            //request.Host = "services3.cic.gc.ca";
            request.ContentLength = 150;
            request.AllowAutoRedirect = false;
              
            if (!string.IsNullOrEmpty(userAgent))  
            {  
                request.UserAgent = userAgent;  
            }  
            else  
            {  
                request.UserAgent = DefaultUserAgent;  
            }  
  
            if (timeout.HasValue)  
            {  
                request.Timeout = timeout.Value;  
            }  
            if (cookies != null)  
            {  
                request.CookieContainer = new CookieContainer();  
                request.CookieContainer.Add(cookies);  
            }  
            //如果需要POST数据  
            if(!(parameters==null||parameters.Count==0))  
            {  
                StringBuilder buffer = new StringBuilder();  
                int i = 0;  
                foreach (string key in parameters.Keys)  
                {  
                    if (i > 0)  
                    {  
                        buffer.AppendFormat("&{0}={1}", key, parameters[key]);  
                    }  
                    else  
                    {  
                        buffer.AppendFormat("{0}={1}", key, parameters[key]);  
                    }  
                    i++;  
                }  
                byte[] data = requestEncoding.GetBytes(buffer.ToString());  
                using (Stream stream = request.GetRequestStream())  
                {  
                    stream.Write(data, 0, data.Length);  
                }  
            }  
            return request.GetResponse() as HttpWebResponse;  
        }  
  
        private static bool CheckValidationResult(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)  
        {  
            return true; //总是接受  
        }  
 
    }
}
